But I've a workaround if you have a diagnostic master request with only one diagnostic slave response. You need for the diagnostics a seperate ldf file. In this file you must define these master request and slave response as a normal frame with diagnostic identifier. The time information at the schedule you must recalculate, that the timing is like at the original ldf. These works faster as with the database example. The timing than is like the schedule at the original ldf.

Than should you take both lin ports at the lin line from your target. At the lin line should be nearly the same timing as with the original ldf with diagnostics at the schedule.

You need the second port at the card to receive the slave response. You need also a a crossing between the send and receive at the ports (Port1 send lin schedule frames and receive diagnostics and Port2 send diagnostics and receive lin schedule frames).

I have similar problem but with NI-XNET 9866 USB. I modified the Ldf file (the original file) to include 2 extra "normal" frames and I named them Diag_send and Diag_read with the id of 3C and 3D. The system works but the problem is I have to wait for a few seconds before I can send another 3C command.